1. Field of the Invention
The present invention relates to an image forming system having a stapler that staples sheets, a sheet post-processing apparatus, and a control method therefor.
2. Description of the Related Art
Conventionally, as apparatuses that staple sheets on which images have been formed by image forming apparatuses such as copiers and printers, post-processing apparatuses equipped with a stapling mechanism that staples a sheet bundle comprised of a plurality of stacked sheets using stapling members such as metallic staples have been widely used. Generally, in a post-processing apparatus of this type, a user sets automatic stapling as an operation mode in image formation from an operation unit of the post-processing apparatus, and the post-processing apparatus automatically carries out a stapling process on a sheet bundle conveyed from an image forming apparatus to the post-processing apparatus. On the other hand, there is also a demand to, aside from an automatic stapling process, carry out a stapling process on a sheet bundle through a manual operation by a user independently of an image forming operation.
As an example of techniques to carry out a stapling process on a sheet bundle by the manual operation, a technique to carry out a stapling process on a sheet bundle by performing a manual operation in which a user inserts the sheet bundle from an opening (sheet discharge port) of a post-processing apparatus (see, for example, U.S. Pat. No. 7,407,156).
According to the technique described in U.S. Pat. No. 7,407,156, when a stapling process is carried out on a sheet bundle by the manual operation, a user accesses the post-processing apparatus from a side thereof on which the opening (sheet discharge port) is provided, and hence it is uneasy for the user to operate the post-processing apparatus. With consideration given to the ease of operation for the user, it is more preferable to access the post-processing apparatus from a front surface thereof. Accordingly, it is conceivable to provide an insertion slot for a sheet bundle in the front surface of the post-processing apparatus.
In a case where a stapling process is to be carried out on only one place at a corner of a sheet bundle, it is unnecessary to insert the sheet bundle to a rear of the post-processing apparatus, and the stapling process is carried out by merely inserting a part of the sheet bundle, on which the stapling process is to be carried out, into an insertion slot provided in a front surface of the post-processing apparatus. Therefore, as compared to a post-processing apparatus configured such that a sheet bundle is inserted into an opening (sheet discharge port) on a side of the post-processing apparatus as described in U.S. Pat. No. 7,407,156, a post-processing apparatus configured such that a sheet bundle is inserted into an insertion slot in a front surface of the post-processing apparatus can enhance the ease of operation for a user.
However, in the case where the stapling process described above is carried out on a sheet bundle, a position at which a stapling mechanism that staples a sheet bundle stands by presents a problem. Ordinarily, there is one stapling mechanism mounted in the post-processing apparatus, and by moving this stapling mechanism, stapling on various places of a sheet bundle can be realized.
This stapling mechanism stands by at a position different from a standby position, which is used in the case of a stapling process manually carried out by a user, considering that a print job in which an image forming process and a stapling process are carried out on sheets by an image forming apparatus having a post-processing apparatus. For this reason, in a case where a user is to carry out a stapling process by a manual operation (manual stapling process), the user has to wait until the stapling mechanism has been moved to the standby position for the manual operation.
Further, if the manual stapling process is to be carried out in a state where the image forming apparatus is in a power-saving state in which power consumption is minimized, a problem explained hereafter will arise. The waiting time that elapses before the manual stapling process is carried out is long due to the need to detect a home position of the stapling mechanism, the need to move the stapling mechanism, and so on, and this stresses the user out.